This invention relates to a process for recovering cellulases. More particularly, it relates to a process for efficiently recovering cellulases wherein a cellulosic material is saccharified by decomposition with cellulases and the residual cellulases are recovered from the resulting saccharified solution in a quite simplified manner.
Recent problems such as energy and food crises and environmental pollution have brought about many studies for effectively utilizing undeveloped resources including those on the saccharification of cellulosic materials.
In particular, enzymatic saccharification has attracted a wide attention since it can be performed in a convenient manner with simple equipment under mild conditions and sugars thus obtained would not further decompose.
However, the expense for the production of enzymes such as cellulases and hemicellulases generally amounts to nearly a half of the total cost of the enzymatic saccharification. Therefore it is very important to recover and reuse expensive enzymes.
Thus, it has been proposed to recover cellulases from a saccharified solution by, for example, ultrafiltration or precipitation with organic solvents.
However, ultrafiltration is very expensive since it must be carried out under an elevated pressure. On the other hand, precipitation with organic solvents is not preferable from the viewpoint of the cost of solvents and the recovery. In addition, each procedure has a disadvantage such that enzymes are highly likely to be inactivated during the treatment.
On the other hand, there has been known a process for accelerating the saccharification of a cellulosic material with a combined use of cellulases originating from fungi belonging to the genera Trichoderma and Aspergillus. However, it is then unavoidable that the yield of the cellulase originating from fungi belonging to the genus Aspergillus is significantly lower than that of the one originating from the genus Trichoderma since the affinity of the former cellulase for the cellulosic material is much lower than that of the latter.